1. Field of the Invention (Technical Field)
The invention relates to an apparatus and method for efficiently moving liquids through liquid spraying systems, in particular for the spray application of paints and lacquers.
2. Background Art
This invention relates to a system for efficient movement of liquids through spraying systems for spray application on surfaces. The apparatus and method of the invention more specifically relate to a manifold apparatus and method for use in high volume, low pressure spray systems, and a customized cap for use therewith.
It is known in the art that the application of surface treatments, such as paints, lacquers, epoxies and the like, can be accomplished using spray systems. It is generally appreciated that paints and lacquers are most rapidly and evenly applied using methods and systems for atomizing them to a spray, and then depositing the spray upon the surface to be covered. In its most commonly encountered form, the existing art consists of the ordinary can of "spray paint." The hand-held can is partially filled with liquid paint and then pressurized, with the result that the opening of a spray nozzle at the top of the can allows the pressurized gas above the contained liquid to expand and force the liquid to spray through the nozzle.
Heavy-duty industrial or construction spray painting systems are typically and essentially mere variations on the basic feature of the ordinary can of spray paint. The common existing system is characterized by the use of high pressure, low volume, air flows. The practice is to fill a metal can or "pot" with paint. The pot is provided with a threaded orifice which allows it to be screwed directly onto a triggered "spray gun." Two tubes, each of a uniform diameter, lead into the interior of the pot: one supplies high pressure to the volume above the liquid paint, the other carries flowing paint from the bottom of the pot directly to the spray nozzle of the gun. Highly pressurized air is also supplied directly to the gun. A jet stream of air at the nozzle of the gun is directed into the stream of flowing paint, thereby atomizing the paint and blowing it toward the surface to be painted.
Common alternative systems incorporate the same basic elements and configuration, but locate the pot remotely from the gun in order to allow the use of larger volume pots. A typical system in the present art is depicted at FIG. 1 of the drawings. In the existing art, pots are generally wide-mouthed and made of light metallic alloys. In such a system, the pot has two widely separated openings in its lid. One opening accommodates a lengthy product line which leads from the bottom of the pot to the spray gun. The other connects the interior of the pot with the bottom opening in a T-joint mounted in the air line. The top two openings in the T-joint are in fluid connection with the air compressor and the spray gun. Air under pressure flows from the compressor to the T-joint, thereby simultaneously delivering air pressure to the interior of the pot as well as the gun. In existing systems, product lines may be of a different diameter than air supply lines, but respective line diameters are consistently uniform throughout their lengths.
Conventional high pressure, low volume spray painting systems are replete with disadvantages. They are inefficient applicators; due to the high pressures used, much of the sprayed liquid is wasted in the form of overspray and "bounceback," with the result that droplets and fumes of the liquid solvents and pigments escape to and pollute the ambient air. Conventional high pressure, low volume systems are also difficult to clean, with the consequent loss of job time. Additionally, existing systems using remotely located product pots are prone to fouling when liquid product backs up or spills out of the pot and into the air lines. A satisfactory description of conventional high pressure, low volume systems and their drawbacks is found in U.S. Pat. No. 4,991,776 to Smith, the disclosure of which is incorporated herein by reference.
To avoid the undesirable bounceback and overspray effects associated with low volume, high pressure spraying systems, systems utilizing high volume and low pressure have been introduced into the art. Such systems employ air discharged at comparatively low pressures to atomize and apply the liquid surfactant. A high volume, low pressure spray application system is disclosed in U.S. Pat. No. 4,991,776.
A disadvantage of high volume, low pressure systems is a tendency for the liquid to be applied inefficiently due to the reduced system pressure. Optimum surface coverage occasionally is achieved only after multiple passes of the spray gun, requiring increased time and user skill. Delivery of liquid product to the gun may be inconsistent and nonuniform. Inconsistency and inefficiency of existing high volume, low pressure systems is seriously aggravated when the pot containing the liquid to be sprayed is located remotely from the spray gun, such as depicted in U.S. Pat. No. 4,991,776. In these instances, when the user elevates the gun above the level of the pot--especially, for example, when standing on a ladder to spray a ceiling--the resulting height differential, coupled with the low system pressure, seriously impedes the discharge and delivery of liquid product to the gun. Varying height differentials cause varying product discharges. The resulting slow and uneven product discharge tires the user and may adversely effect the quality of the surface finish.
U.S. Pat. No. 888,693 to Aranguren y Bustinza, entitled Paint Machine, discloses a device employing pressurized air and allowing the user consecutively to apply more than one color of paint without having to change paint containers or switch devices.
U.S. Pat. No. 3,802,511 to Good, Jr., entitled Portable Fire Extinguisher, discloses an apparatus for using air pressure to power a hand-held water pump for generating a stream of water.
U.S. Pat. No. 3,945,571 to Rash, entitled Self-Contained Portable Pressure Apparatus and Hand Gun Assembly, discloses a device permitting the user to carry on her back a portable vessel of pressurized air, and in her hand a triggered gun affixed below a hopper containing a surface coating mix. Pressurized air flows from the vessel, through the hopper and to the gun nozzle. The surface coating mix flows by gravity and is never under pressure.
U.S. Pat. No. 3,940,065 to Ware et al., entitled Portable Spraying Apparatus, discloses a self-contained device for directly pumping paint. An electrically powered, readily primed paint pump acts directly on the paint to force it through a supply line to a gun. No compressed air is utilized.
U.S. Pat. Nos. 4,991,776 and 5,044,557 and 5,058,807 to Smith, all entitled High Volume, Low Pressure Spraying System, disclose devices for generating a high volume, low pressure air delivery system for use in spraying applications. The device attaches to standard air compressors and converts high-pressure low-volume air flow to a low-pressure, high-volume air flow to the spray gun through the use of a Venturi induction pump. The delivery of paint, however, is by standard means of pressure pots; nothing is taught regarding the enhancement of the paint flow from the pressure pots to the spray guns.
Accordingly, there remains a need for an apparatus and method for increasing the product delivery efficiency and reliability of high volume, low pressure spraying systems. There is also a need for such an apparatus and method that minimizes the time and effort involved in cleaning the system after each use.